V. BIOGENESIS AND METABOLISM 



281 



ley-Maclean^ has shown by means of polybromide analysis that the poly- 

 unsaturated acids decrease in rats in a deficiency state and that curing the 

 deficiency with linoleate restores the polyunsaturated content of the animal . 

 By means of the spectrophotometric method of analysis, this has been 

 verified in greater detail, showing that, when supplements of different oils'^ 

 or pure fatty acids^ are made, changes take place in the polyunsaturated 

 fatty acids in the animal, depending on the substance fed. From these 

 studies it appears that the dominant interconversions in some tissues are 

 the synthesis of arachidonate from linoleate and hexaenoate from linolenate. 

 Increases of pentaenoate were observed in blood and kidney as the result 

 of linolenate supplementation in fat-deficient rats.^ Hearts of fat-deficient 



HEART 6 1= 

 3 



HEART 4 r 



N= NORMAL CONTROL 

 D= FAT DEFICIENT 

 = STEARATE (no I- ) 



1 = OLEATE (If) 



2 = LINOLEATE (21=) 



3 = LINOLENATE (3 1=) 



4 = ARACHIDONATE (4 1= ) 



Fig. 3. Changes in the polyunsaturated fatty acids of the heart and kidney as 

 the result of single fatty acid supplementation. ^■i" 



rats accumulate a high proportion of trienoic acid which is not normally 

 present.'' The administration of arachidonate to fat-deficient rats results 

 in its slow deposition.^ During a period of 7 weeks daily supplementation 

 with 30 mg. of methyl arachidonate, the total arachidonate content of the 

 animals increased equivalent to only 10 % of that fed. The recovery in poly- 

 unsaturated acid content of the animal parallels the slow recovery from the 

 deficiency disease and emphasizes the low rate of turnover of these acids in 

 the tissue. The typical metabolic changes in polyunsaturated acids are il- 



* I. Smedley-Maclean, The Metabolism of Fat. Methuen & Co., London, 1943. . 

 ^ I. G. Rieckehoff, R. T. Holman, and G. O. Burr, Arch. Biochem. 20, 331 (1949). 

 « C. Widmer and R. T. Holman, Arch. Biochem. 25, 1 (1950). 

 9 R. T. Holman and T. S. Taylor, Arch. Biochem. 29, 295 (1950). 

 *" R. T. Holman, Proc. 3rd Conf. on Research, Am. Meat. Inst. Univ. Chicago p. 1 

 (1951); Fette u. Seifen 53, 332 (1951). 



